Direct numerical simulations are conducted to investigate in detail the effect of Mach number on vortex pairing in a mixing layer. The pairing process is found to be delayed at higher Mach numbers and the paths followed by the vortices change. To investigate the effect of the initial shape of the vortices a simple vortex dynamical model of pairing is constructed which accurately models pairing ...

The Breguet range equation indicates that to the first order of approximation range will be maximized by maximizing ML/D, where M is the Mach number and L/D is the lift/drag ratio. Since the drag coefficient increases very rapidly as the Mach number approaches one, this leads to the design of a long range aircraft which fly at high subsonic speeds, typically in the range Mach 0.8 to 0.85, just ...

SUMMARY An asymptotic analysis of the compressible Euler equations in the limit of vanishing Mach numbers is used as a guideline for the development of a low Mach number extension of an explicit higher order shock capturing scheme. For moderate and large Mach numbers the underlying explicit compressible ow solver is active without modiication. For low Mach numbers, the scheme employs an operato...

Achromatic second-order (contrast) Mach bands can be perceived near the contrast ramp between two contrast levels. In this study we show that a repertoire of chromatic second-order Mach bands is also clearly perceived, under equal-luminance conditions (minimum motion technique). The results show that chromatic and achromatic second-order stimuli yield significant perceived second-order Mach ban...

Mach bands are the illusory dark and bright bars seen at the foot and knee of a luminance trapezoid. First demonstrated by Ernst Mach in the latter part of the 19th century, Mach bands are a test bed not only for models of brightness illusions but of spatial vision in general. Up until 50 years ago the dominant explanation of Mach Bands was that they were caused by lateral inhibition among reti...

In this study we propose a new numerical algorithm for droplet-laden turbulent channel flow with phase transitions at low Mach numbers. The carrier gas is treated as compressible flow. In order to avoid very small time steps at low Mach numbers that would arise from stability requirements associated with explicit time-stepping we propose a new semi-explicit time integration method, applied to t...

[1] Radiating shear and Rayleigh waves from supershear ruptures form Mach waves that transmit large-amplitude ground motion and stresses to locations far from the fault. We simulate bilateral ruptures on a finite-width vertical strike-slip fault (of width W and half-length L with L W) breaking the surface of an elastic half-space, and focus on the wavefield out to distances comparable to L. At ...

The achromatic Mach bands effect is a well-known visual illusion, discovered over a hundred years ago. This effect has been investigated thoroughly, mainly for its brightness aspect. The existence of Chromatic Mach bands, however, has been disputed. In recent years it has been reported that Chromatic Mach bands are not perceived under controlled iso-luminance conditions. However, here we show t...

We introduce continuous tools to study the low Mach number behavior of the Godunov scheme applied to the linear wave equation with porosity on cartesian meshes. More precisely, we extend the Hodge decomposition to a weighted L space in the continuous case and we study the properties of the modified equation associated to this Godunov scheme. This allows to partly explain the inaccuracy of the G...

This paper is devoted to the low Mach number limit of weak solutions to the compressible Navier-Stokes equations for isentropic uids in the whole space R d (d = 2 or 3). This problem was investigated by P.L. Lions and N. Masmoudi 19]. We present here a diierent approach based upon Strichartz' estimates for the linear wave equation like in 21] in the inviscid case, which improves the convergence...